no-assert-equal.js

// Copyright 2020 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * @fileoverview Rule to ban usage of assert.equal
 * @author Jack Franklin
 */
'use strict';

// ------------------------------------------------------------------------------
// Rule Definition
// ------------------------------------------------------------------------------

/**
 * @type {import('eslint').Rule.RuleModule}
 */
module.exports = {
  meta: {
    type: 'problem',

    docs: {
      description: 'Usage of assert.equal',
      category: 'Possible Errors',
    },
    fixable: 'code',
    schema: [], // no options
  },
  create: function (context) {
    return {
      CallExpression(node) {
        if (
          node.callee.type === 'MemberExpression' &&
          node.callee.object.name === 'assert' &&
          node.callee.property.name === 'equal'
        ) {
          context.report({
            node,
            message:
              'assert.equal is non-strict. Use assert.strictEqual or assert.deepEqual to compare objects',
            fix(fixer) {
              /**
               * Get the type of the second argument and try to match it to a assert type
               */
              const compareToType = node.arguments.at(1)?.type;
              if (
                // Match number or string
                compareToType === 'Literal' ||
                // Match `` string
                compareToType === 'TemplateElement'
              ) {
                return fixer.replaceText(node.callee.property, 'strictEqual');
              }
              if (
                // Match any object `{...}`
                compareToType === 'ObjectExpression' ||
                // Match any array `[...]`
                compareToType === 'ArrayExpression'
              ) {
                return fixer.replaceText(node.callee.property, 'deepEqual');
              }
            },
          });
        }
      },
    };
  },
};